//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
#include "util/file_util.h"

#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <unistd.h>

#include <algorithm>
#include <string>

#include "rocksdb/env.h"
#include "util/file_reader_writer.h"
#include "util/sst_file_manager_impl.h"

namespace rocksdb {

// Utility function to copy a file up to a specified length
Status CopyFile(Env* env, const std::string& source,
                const std::string& destination, uint64_t size, bool use_fsync) {
  const EnvOptions soptions;
  Status s;
  std::unique_ptr<SequentialFileReader> src_reader;
  std::unique_ptr<WritableFileWriter> dest_writer;

  {
    std::unique_ptr<SequentialFile> srcfile;
    s = env->NewSequentialFile(source, &srcfile, soptions);
    if (!s.ok()) {
      return s;
    }
    std::unique_ptr<WritableFile> destfile;
    s = env->NewWritableFile(destination, &destfile, soptions);
    if (!s.ok()) {
      return s;
    }

    if (size == 0) {
      // default argument means copy everything
      s = env->GetFileSize(source, &size);
      if (!s.ok()) {
        return s;
      }
    }
    src_reader.reset(new SequentialFileReader(std::move(srcfile), source));
    dest_writer.reset(
        new WritableFileWriter(std::move(destfile), destination, soptions));
  }

  char buffer[4096];
  Slice slice;
  while (size > 0) {
    size_t bytes_to_read = std::min(sizeof(buffer), static_cast<size_t>(size));
    s = src_reader->Read(bytes_to_read, &slice, buffer);
    if (!s.ok()) {
      return s;
    }
    if (slice.size() == 0) {
      return Status::Corruption("file too small");
    }
    s = dest_writer->Append(slice);
    if (!s.ok()) {
      return s;
    }
    size -= slice.size();
  }
  return dest_writer->Sync(use_fsync);
}

// Utility function to create a file with the provided contents
Status CreateFile(Env* env, const std::string& destination,
                  const std::string& contents, bool use_fsync) {
  const EnvOptions soptions;
  Status s;
  std::unique_ptr<WritableFileWriter> dest_writer;

  std::unique_ptr<WritableFile> destfile;
  s = env->NewWritableFile(destination, &destfile, soptions);
  if (!s.ok()) {
    return s;
  }
  dest_writer.reset(
      new WritableFileWriter(std::move(destfile), destination, soptions));
  s = dest_writer->Append(Slice(contents));
  if (!s.ok()) {
    return s;
  }
  return dest_writer->Sync(use_fsync);
}

Status DeleteSSTFile(const ImmutableDBOptions* db_options,
                     const std::string& fname, const std::string& dir_to_sync) {
  return DeleteDBFile(db_options, fname, dir_to_sync, false);
}

Status DeleteDBFile(const ImmutableDBOptions* db_options,
                    const std::string& fname, const std::string& dir_to_sync,
                    const bool force_bg) {
#ifndef ROCKSDB_LITE
  auto sfm =
      static_cast<SstFileManagerImpl*>(db_options->sst_file_manager.get());
  if (sfm) {
    return sfm->ScheduleFileDeletion(fname, dir_to_sync, force_bg);
  } else {
    return db_options->env->DeleteFile(fname);
  }
#else
  (void)dir_to_sync;
  (void)force_bg;
  // SstFileManager is not supported in ROCKSDB_LITE
  return db_options->env->DeleteFile(fname);
#endif
}

int SetThreadSched(SchedClass sched_class, int nice) {
#ifdef OS_LINUX
  sched_param s;
  s.sched_priority = 0;
  if (sched_class == kSchedOther) {
    int ret = sched_setscheduler(0, SCHED_OTHER, &s);
    if (ret != 0) {
      return ret;
    }
    return setpriority(PRIO_PROCESS, 0, (nice < -20 || nice > 19) ? 0 : nice);
  }
  if (sched_class == kSchedBatch) {
    return sched_setscheduler(0, SCHED_BATCH, &s);
  }
  if (sched_class == kSchedIdle) {
    return sched_setscheduler(0, SCHED_IDLE, &s);
  }
  return -1;
#else
  (void)sched_class;
  (void)nice;
  return 0;
#endif
}

}  // namespace rocksdb
